Giant horsetails are usually living

species In biology, a species is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of ...

horsetail ''Equisetum'' (; horsetail, snake grass, puzzlegrass) is the only living genus in Equisetaceae, a family of ferns, which reproduce by spores rather than seeds. ''Equisetum'' is a "living fossil", the only living genus of the entire subclass E ...

that grow to very large sizes, more than 1.5 metres (5 ft). The following species are commonly known as "giant horsetails": * '' Equisetum giganteum'' (southern giant horsetail, from Latin America) * ''

Equisetum telmateia ''Equisetum telmateia'', the great horsetail or northern giant horsetail, is a species of '' Equisetum'' (puzzlegrass) with an unusual distribution, with one subspecies native to Europe, western Asia and northwest Africa, and a second subspeci ...

'' (northern giant horsetail, from North America, North Africa and Eurasia) * '' Equisetum myriochaetum '' (Mexican giant horsetail, from Mexico,

Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. C ...

and Northern South America) In addition, any giant member of the Equisetopsida (horsetails and their

prehistoric Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use o ...

relatives) is liable to be called "giant horsetail" even though they are not true horsetails. Most often, the term "giant horsetail" in this somewhat inaccurate sense refers to

Calamitaceae Calamitaceae is an extinct family of plants related to the modern horsetails. Some members of this family attained tree-like stature during the Carboniferous Period (around ) and in Permian Period, reaching heights of up to 20 meters. The famil ...

in Paleozoic contexts; in the Mesozoic, the term usually refers to the '' Equisetites'' assemblage. The oldest known fossil of giant horsetail dates from Miocene epoch and is found in Ñirihuau Formation in Patagonia.

References

{{Plant common name